Production of ammonium nitrate.



users units Y,;"i;i Flinn To all whom it may concern'. Be'it known that we, EnN's'r Robots-(Jasmine a sub- ,ject of the Kingfoi Prussia, residing at erdingen-om a thedthinexGermany, joi'ro NYDEGGER asCltlZen of :the Republic-of Switzerland, residing at Uerdingen- --on-the-Rhine, Germany, and Aaron Gonnscnnrn'r, a subjectol tlie K ingfbflPrussia, residing at Di'isseldorf, erma y, hays invented certain new and useful '11!!- ;provements;-in andaRelating touthe Production of Ni -trate of akmmoniumpand we do hereby declare the folf lowi o beafiill ile'ar", and exact description of the fib es i n-5'.

Previous attempts to replace the usual process oi.t'ormation of nitrate of ammonium from n'itric 7 acid and m n 'nia' a cheaper process of double decompositioiiiirom nitrate of sofdawith sulfate-of ammonium havetproyv, l1nnsuecessftil 'becausethe nitrate of am monium produced has not possessed the desired purity.

Under a recent German patent (now expired) No. 149026 of February 3, 1903, the troublesome double salt formationof non-decomposed sulfate of ammonium with sulfate of sodium and nitrate of sodium is lessened by the application of a surplus of nitrate of sodium, which, however, for the purpose of economically carrying out the process must amount to at least one hundred per cent (100% )'of the quantity theoretically necessary." But the Letters Patent makes no statement as to the production of pure nitrate of ammonium from this mixture of nitrate of ammonium, sulfate of sodium, and nitrate of sodium, and thus the object: of the present process is not attained. i Another German Patent No. 166746 was granted on September 8, 1903 (the correspondingU. S. Patent No. 764251 on July 5, 1904) for a process which is impracticable as involving a costly artificial cooling step and as being subject to the hazard of the slight accident of jarring which injuriously affectsthe result. See page 3 line 54 et seq. of U. S. Patent 764251. The specification of this patent also discloses that in this process, an unusual procedure is necessary to successfully separate the salts of sodium from the nitrate of ammonium. In contrast to the older processes above described,

. our process makes it practically possible to carryout the double decomposition smoothly, to separate sul-' fate of sodium and nitrate of sodium as such, and to gain pure nitrate of ammonium direct-1y.

' The relations of solubility of the two salts of sodium were examined in the presence of nitrate of ammonium and the following results were obtained:

A mixed solution of nitrate of sodium and sulfate of ammonium, which contains at least twenty per cent (20%) more nitrate oi sodiun'ijhan is theoretically necessary for double decompoaitiiiil, yields sulfate of sodium plen- 4 gpeci fic at ion of Letters Patent. "12 Application filed October 2,19062 Burial No. 337,121,

ointmenanama er, 907.

I tiiully on evaporation to a temperature of'about 114",

If the evaporation is continueduntil the-solution, at

about 35 or atahigher temperature, is saturated withnitrate of ammoni m, mostof the sulfate of sodium formedby the double decomposition is crystallized out. This is'due to the presence oi nitrate of sodium nearly to saturation, in the solution. which not only "causes the double decomposition to proceed smoothly "but effects "the crystallization of the'sulfate of sodium. Now, this solution ht atempera'ture near the point ,of' crystallization of. nitrate of ammonium which takes place, accordiii g, to the extent of evaporation at about 35or'even at a'higher temperature-crystallizes outquantities of nitrate of sodium sufficient for .the success of the process, and afurthe'r portion of sulfate of sodium; For, in proportion to the amount of the surplus of nitrate of sodium, KSNYGH as in proportion to the hereinbeiorc mentioned degree of evaporation and the concentration of nitrate of ammonium in'connection therewith, when the hot solution is cooled off. at about 50 or even at a higher temperature, complete saturation of the solution with nitrate of sodium ensues, which, besides the cooling, tends to separate the sulfate of sodium still in solution. So,also, the complete saturation of the solution with sulfate of sodium, which always exists during the cooling, tends to crystallize out the nitrate of sodium. This action is so noticeable that considerably more nitrate of sodium is crystallized than would be expected from its solubilty in water.

The portion of the sulfate of sodium and of the nitrate of sodium which has been cystallized in the manner described by mutual salting out from hot solutions supersaturated with both soda salts, are then removed from the solution; The portion of the soda salts still. in solution therein has, as has been found furthermore, the desirable effect that far more nitrate of ammonium remains dissolved in the hot solution than would be ex- 'pected from its solubility in water. On the other hand,

when the temperature falls below +30, less nitrate of ammonium remains in solution than corresponds to its solubility in water. From these relations of solubility there appeared a means of effecting a large yield of nitrate of ammonium, by applying temperatures above +35", as above indicated, for the separation of the salts of soda from the solution almost saturated with nitrate oframmoniumf an'd using temperatures below +35"ior the separation of the nitrate of ammonium.

The solution almost saturated with nitrate of ammonium at 35 or at a higher. temperature would, during the cooling, permit solid soda salts to be crystallized out as well as much nitrate of ammonium;

, but as the industry 0; e gploaives demands a. very pure nitrate oi ammonium, this invention aims at procuring pure nitrate oi ammonitun directly from the hot solution. Such a pure product is secured in this i process by adding so muchwater to the warm solution before cooling th'at the soda salts at the temperature I to which they are' cooled of ffor example, at say 5 +20 remain in solution.

small scale'it can be determined how much water is By experiments on a necessary to keep the nitrate of ammonium tree from the crystallization of the soda salts. ,It generally suflices to add from one-fifth to one-seventh of the weight of the solution.

the nitrate of ammonium remains dissolved.

The processof this invention is illustrated in the following example: 645 parts .ofnitrate of sodium (of .which is surplus) and 400 parts of'snliateof ammonium are. heated with 800 parts of water, so that 20 a complete double decomposition can take place. The

mixture must then be evaporated until a sample of v the'solution. filtered off from the separated sulfate of sodium, oncooling to about 70 begins to separate nitrate. of ammonium. The technical separation of '25 sulfate of sodium from the'solution is facilitated, however, if the solution is filtered even before thisconicentration is reached, for instance, when it showsv a boiling point of about 118.

When the desired concentration has been attained,

the solution is cooled off to nearly 70. In this case it is already saturated with nitrate of sodium at about 80. After the crystallized nitrate of sodium and sulfate of sodium have been removed from the solusolutlon to about 15 ample, about 16 parts of water are added to 100 parts of the solution obtained, in order to attain this end.

The solution thus diluted is then cooled off to the desired temperature during which about 40% of the vnitrate of ammonium, the same is liberated from the solution. The nitrate of ammonium thus produced yields 25 to 30% of the theoretical amount ofthis salt and the purity of the product is 99 to 100%. Q

I I claim as my invention The process of producing pure nitrate of ammoniuln from nitrate of sodium and sulfate of ammonium. which consists in adding nitrate of sodium to a solution of sulfate of ammonium until the mixture is supersaturated with the former at a temperature over about 49 C., coolabovethe saturation point of nitrate of ammonium, there by rystallizing out most of the sodium sulfate and sodium nitrate drawing off the'solution from the crystallized so dium salts, adding water equal to about one-fifth to one seventh the weight of the solution. to keep the soda salts dissolved during the remainder of the process, cooling this to 20 C. thereby crystullizing out the ammonium nitrate and removing the nitrate of ammonium which has crystallized out. w p

. In testimony whereof we have signed our names to this specification, in the presence of two subscribing witnesses.

ERNST RUDOLF CASIARI.

OTTO NYDEGGER. ANT-ON GOLDSCHMIDT. Witnesses:

W. BRUCE 'ALLACE, MARGARET WALLACE.

ing thissolutionto the temperature of about 35 C. Just 

